British Airways shareholders will hold a series of urgent meetings with the airline's chairman and chief executive this week as the City seeks assurances that lessons have been learned from the Heathrow Terminal 5 fiasco.

BA's chairman, Martin Broughton, will sit down with David Cummings, head of equities at Standard Life Investments, and Guy Jubb, SLI's head of corporate governance, to reassure the fund manager that the board is on top of the situation.

SLI, one of the airline's biggest investors, is also due to meet Willie Walsh, BA chief executive, tomorrow to hear an explanation of what went wrong when T5 opened and how it is being fixed. Broughton said the meetings had been brought forward at SLI's request.

A BA spokesman said the airline would meet several major shareholders this week. "We are more than happy to discuss with large shareholders any questions they have regarding the opening of T5," he said. Walsh is also expected to meet Invesco Perpetual, BA's biggest shareholder, this week.

In an interview published this weekend, Broughton described the botched opening of T5, which led to more than 500 flights being cancelled and nearly 30,000 bags being lost, as an "acute embarrassment". However, he gave his backing to the embattled Walsh, who has refused to resign despite taking personal responsibility for the crisis.

"Willie has been a great success. If it had not been for the embarrassment of T5 we would be hailing this as the end of an extremely successful year. He's done a lot of things for the customer and he's done a lot of things on industrial relations," Broughton told the Sunday Telegraph. He also admitted that television footage of disgruntled passengers waiting for check-in, refunds or delayed baggage could be very damaging to the business.

"Passengers remember their last trip. The ability to win them back is there, but we have upset them," he said.

BA has said the T5 launch had cost it £16m in lost revenues and passenger compensation, a relatively low amount for the disruption caused. The majority of T5 flights have been short-haul, while BA's most lucrative long-haul routes, such as Heathrow to New York, were kept at Terminal 4 temporarily.

The long-haul flights will be kept at T4 longer because of T5's troubled debut. The decision to further delay the transfer of BA's long-haul services to T5 could be costly, however, because rebooking passengers caught out by the move on to alternative flights will be more expensive.

Jonathan Strickland, an airline consultant, said some passengers would miss connecting flights because the summertime T5 schedule has been built around the presumption that passengers will be flying in and out of the building, rather than transferring through T4.

"This will be inconvenient for customers and revenue-losing for BA," said Strickland. "Flights will have been sold on the basis of a short connection time. It could potentially be a big revenue hit for BA. Once you get long-haul flights involved, the figures start ratcheting up."

Shareholders are also expected to seek assurances that other pressing issues in Walsh's in-tray are not being neglected while BA gets to grips with T5. Rival carriers are taking advantage of the Open Skies treaty that liberalises the transatlantic market, allowing any EU-based carrier to fly to the US and vice versa.

The UK flag carrier's Heathrow base is under unprecedented pressure as a result, with more than 7,000 extra seats a week between London airports and New York.

BA has set up an airline called Open-Skies in response to the treaty but its launch is in doubt after the airline's pilots voted to strike over the move.

The carrier is challenging the pilots' right to strike and their union, Balpa, has asked a judge to rule whether the industrial action is legal.